Visible and infrared light source for illumination system and projection device comprising the same

ABSTRACT

An illumination system and a projection device comprising the same are provided. The projection device comprises an image-forming system and the illumination system. The illumination system comprises a first light source device, a second light source device and a first light guiding device. The first light source device generates a visible light, while the second light source device directly generates a substantially pure infrared light. The first light guiding device is adapted to guide the visible light and the infrared light to the image-forming system for processing to make the visible light form a visible light image and make the infrared light form an infrared light image.

This application claims priority to Taiwan Patent Application No.099127914 filed Aug. 20, 2010, the disclosures of which are incorporatedherein by reference in their entirety.

CROSS-REFERENCES TO RELATED APPLICATIONS

Not applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an illumination system for a projectiondevice, and more particularly, to an illumination system for aprojection device adapted to generate a visible light image and aninfrared light image.

2. Descriptions of the Related Art

Human eyes can only see the visible light with wavelength ranging fromapproximately 400 nm to 700 nm. However, at night or when the visiblelight becomes faint, light (e.g., moonlight or starlight) irradiatedfrom the objects in the natural environment has wavelength mainlyranging from approximately 700 nm to 1,000 nm, so human eyes cannot seethe objects in such environment. In particular, it is critical formilitary operations to see clearly the targets at night. Therefore, inmilitary and civil aviation applications, simulation at night with atraining simulator is one of the primary training programs for aviationtraining. A common night vision goggle (NVG) can convert the light withwavelength between 650 nm and 880 nm (mainly an infrared light) into avisible light with wavelength between 400 nm and 700 nm. In most cases,human eyes preferably receive visible light with wavelength of about 550nm that is converted by the NVG.

In reference to FIGS. 1A and 1B, a conventional night vision projector 1can generate a visible light image and an infrared light image. Inreference to FIG. 1A, during the simulation of a visible light image, byturning on a light source 11 and turning off a light source 12, a lightray 11 a generated by the light source 11 passes through a visible lightfilter 112, is then reflected by reflectors 131, 133 to a lightprocessing element 14 to be processed into a visible light image, and isfinally projected outward via a lens 15. In reference to FIG. 1B, duringthe simulation of a night vision image, by turning off the light source11 and turning on the light source 12, a light ray 12 a generated by thelight source 12 is filtered by an infrared light filter 122 into aninfrared light, is then reflected by reflectors 132, 134 to the lightprocessing element 14 to be processed into an infrared light image, andis finally projected outward, also via the lens 15, to present aninfrared light image. At this point, the user observes the infraredlight image by using the NVG to simulate conditions at night. However,both the light ray 11 a and the light ray 12 a emitted by the lightsources 11, 12 have to be filtered through the visible light filter 112and the infrared light filter 122 and then be reflected by thereflectors 131, 132, 133, 134 multiple times respectively to form thevisible light image and the infrared light image respectively;therefore, the light ray 11 a and the light ray 12 a are continuouslyattenuated during the filtering process and the multiple reflectionsdescribed above, which affects the luminance of the generated images.Furthermore, the visible light filter 112 and the infrared light filter122 will absorb a great deal of light energy that is filtered out andthus, generates a great deal of heat energy, resulting in many problems.On the other hand, the night vision projector 1 of this kind usually hasdisadvantages, such as a bulky volume due to the numerous elementstherein.

FIG. 2 illustrates another conventional night vision simulation system2. A tracking element 24 tracks the viewing direction of a night visiongoggle 21, an image generator 23 controls a display 22 to generate acorresponding red light image for output to the night vision goggle 21according to the viewing direction of the night vision goggle 21. Inthis way, although the user can experience the image that is saw when anight vision goggle is used, this simulator requires complicated andprecise parts and fails to allow multiple persons to see the sameinfrared light image at the same time, which reduces their the feelingof presence of drilling at night. On the other hand, conventional nightvision simulation system 2 cannot provide a visible light image; andwhen a visible light image is to be provided for use in daylight,another auxiliary apparatus is required.

In view of this, a need exists in the art to provide an illuminationsystem for a projection device, which can provide both a common visiblelight image and an infrared light image for simulating conditions atnight without the need of complicated parts and apparatuses and also,can increase the luminance and the light utilization efficiency andreduce the generation of heat energy.

SUMMARY OF THE INVENTION

The primary objective of the present invention is to provide aprojection device capable of providing both a visible light image and aninfrared light image and an illumination system thereof, which haveadvantages as a high luminance, a high light utilization efficiency andlow generation of heat energy.

To achieve the aforesaid objective, a projection device of the presentinvention comprises an image-forming system and an illumination system.The illumination system comprises a first light source device, a secondlight source device and a first light guiding device. The first lightsource device generates a visible light, while the second light sourcedevice directly generates a substantially pure infrared light. The firstlight guiding device guides the visible light and the infrared light tothe image-forming system for processing to make the visible light form avisible light image and make the infrared light form an infrared lightimage.

The detailed technology and preferred embodiments implemented for thesubject invention are described in the following paragraphs accompanyingthe appended drawings for people skilled in this field to wellappreciate the features of the claimed invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic view of a conventional night vision projectorsimulating a visible light image;

FIG. 1B is a schematic view of the conventional night vision projectorsimulating an infrared light image;

FIG. 2 is a schematic view of a conventional night vision simulationsystem;

FIG. 3A is a schematic view of the first embodiment of the presentinvention;

FIG. 3B is a schematic view showing the output of light rays ofdifferent wave bands according to the time sequence according to thefirst embodiment of the present invention;

FIG. 4A is a schematic view the output of a visible light imageaccording to the second embodiment of the present invention;

FIG. 4B is a schematic view showing the output of an infrared lightimage according to the second embodiment of the present invention; and

FIG. 5 is a schematic view of the third embodiment of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Firstly, in reference to FIG. 3A, the projection device 5 of the presentinvention comprises an image-forming system 4 and an illumination system3. The illumination system 3 comprises a first light source device 31, asecond light source device 32 and a first light guiding device 33. Thefirst light source device 31 is adapted to generate a visible light L,while the second light source device 32 is an infrared light source. Thesecond light source device 32 directly generates a substantially pureinfrared light IR without using an infrared light filter or adoptingother indirect ways. The first light guiding device 33 is adapted toguide the visible light L and the infrared light IR to the image-formingsystem 4 for processing so that the visible light L forms a visiblelight image and the infrared light IR forms an infrared light image.

The second light source device 32 directly generates the substantiallypure infrared light, which has wavelength ranging from 650 nm to 880 nm.This wavelength range conforms to the spectral response of a nightvision goggle, so the infrared light can be saw through the night visiongoggle to simulate conditions at night. Furthermore, the first lightguiding device 33 comprises a dichroic layer, which allows the visiblelight L to pass therethrough, but reflects the infrared light IR to theimage-forming system 4.

In the present invention, the image-forming system 4 comprises a lightprocessing element 41 for making the visible light L and the infraredlight IR form a visible light image and an infrared light imagerespectively. The light processing element 41 may be a liquid crystaldisplay (LCD) element, a digital micromirror device (DMD), or a liquidcrystal on silicon (LCOS) element. Moreover, the projection device 5 ofthe present invention may be an apparatus with projection and displayingfunctions such as a digital light processing (DLP) projection device ora liquid crystal display (LCD) projection device.

For convenience of description, the preferred embodiments of the presentinvention will be explained in detail hereinafter. It shall beappreciated that the preferred embodiments of the present invention arenot intended to limit the present invention to any specific environment,applications or particular implementations described in the preferredembodiments. Therefore, the description of the preferred embodiments isonly for the purpose of illustration rather than to limit the presentinvention.

The first embodiment of the present invention is shown in FIG. 3A andFIG. 3B. As shown in FIG. 3B, the first light source device 31 and thesecond light source device 32 emit a red light R, a green light G, ablue light B and an infrared light IR respectively by time sequencecontrol. In reference to FIG. 3A, after being emitted by the first lightsource device 31 according to the time sequence, the red light R, thegreen light G and the blue light B pass through the first light guidingdevice 33 and are outputted to the light processing element 41 of theimage-forming system 4 for processing. The red light R, the green lightG and the blue light B are processed into a red light image, a greenlight image and a blue light image respectively by the light processingelement 41, and are projected outward to form a visible light imagethrough superposition. Then, subsequent to the first light source device31, the second light source device 32 emits the infrared light IR. Theinfrared light IR is reflected and guided by the dichroic layer of thefirst light guiding device 33 to the image-forming system 4, where it isprocessed into an infrared light image by the light processing element41 for projection outward.

The first light source device 31 preferably comprises a red lightemitting diode, a green light emitting diode and a blue light emittingdiode, which emit the red light R, the green light G and the blue lightB respectively by a time sequence control; and the second light sourcedevice 32 may be an infrared light emitting diode which directly emitsthe substantially pure infrared light IR. Alternatively, the first lightsource device 31 comprises a red laser light source, a green laser lightsource and a blue laser light source, which emit the red light R, thegreen light G and the blue light B respectively by a time sequencecontrol; and the second light source device 32 may be an infrared laserlight source which directly emits the substantially pure infrared lightIR.

In addition, it shall be appreciated that in other variants, the firstlight source device 31 may comprise a combination of the aforesaid laserlight sources and light emitting diodes, for example, a combination ofthe red laser light source, the green light emitting diode and the bluelight emitting diode. Furthermore, the green light G may also begenerated through excitation of a green phosphor (not shown) by the bluelaser light source or the blue light emitting diode. Likewise, theinfrared light IR may also be emitted by a combination of the infraredlight emitting diode and the infrared laser light source.

It can be readily inferred by those of ordinary skill in the art thatthe aforesaid first light guiding device 33 of this embodiment may havea dichroic layer with opposite characteristics and the position of thefirst light source device 31 may be exchanged with that of the secondlight source device 32. In this case, the first light guiding device 33can also reflect the visible light L generated by the first light sourcedevice 31 to the image-forming system 4, and allow the infrared light IRgenerated by the second light source device 32 to pass therethrough tothe image-forming system 4, thereby generating and projecting thevisible light image and the infrared light image.

The second embodiment of the present invention is shown in FIG. 4A andFIG. 4B. The second embodiment of the present invention differs from thefirst embodiment in that the first light source device 31 is a whitelight source and the illumination system 3 further comprises a colorwheel 34 and a switch device 35. By controlling the color wheel 34according to the time sequence, the visible light L from the first lightsource device 31 is filtered into the red light R, the green light G andthe blue light B respectively according to the time sequence whenpassing through the color wheel 34.

In this embodiment, the first light source device 31 may be a whitelight emitting diode, a high intensity discharge (HID) lamp or an ultrahigh pressure (UHP) lamp. The second light source device 32 may be aninfrared light emitting diode (LED) or an infrared laser light source.

In reference to FIG. 4A, the first light source device 31 of thispreferred embodiment is a white light source, so the color wheel 34 mustbe disposed between the first light guiding device 33 and theimage-forming system 4. The color wheel 34, which comprises a redsector, a green sector, a blue sector and a transparent sector, canfilter the visible light L of the first light source device 31 into ared light R, a green light G and a blue light B respectively by a timesequence control and allow the infrared light IR of the second lightsource device 32 to pass through the transparent sector. The switchdevice 35 is disposed between the first light source device 31 and thefirst light guiding device 33 to control the visible light L enteringthe first light guiding device 33. The first light guiding device 33 isadapted to guide and output the visible light L and the infrared lightIR to the light processing element 41 of the image-forming system 4 forprocessing so that the visible light L forms the visible light image andthe infrared light IR forms the infrared light image. This process willbe described in more detail hereinafter.

In reference to FIG. 4A, the first light source device 31 continuouslyemits the visible light L; and when the switch device 35 is far awayfrom the first light source device 31, the switch device 35 allows thevisible light L from the first light source device 31 to enter the firstlight guiding device 33. In this case, the second light source device 32is turned off. After the visible light L passes through the first lightguiding device 33, the color wheel 34 is sequentially rotated to the redsector, the green sector and the blue sector by a time sequence controlso that the visible light L is filtered into the red light R, the greenlight G and the blue light B respectively by the color wheel 34.Finally, the red light R, the green light G and the blue light B areoutputted to the image-forming system 4 where they are processed by thelight processing element 41 into the red light image, the green lightimage and the blue light image respectively, and are then projectedoutward to form the visible light image through superposition.

In reference to FIG. 4B, when the color wheel 34 is rotated to thetransparent sector, the switch device 35 is located in front of thefirst light source device 31 to prevent the visible light L fromentering the first light guiding device 33, thereby preventing thevisible light L from entering the image-forming system 4 and the lightprocessing element 41. In this case, the second light source device 32is turned on, and directly emits the substantially pure infrared lightIR to the first light guiding device 33. The first light guiding device33 reflects the infrared light IR to the color wheel 34. At this point,the color wheel 34 is controlled according to the time sequence to allowthe infrared light IR to pass through the transparent sector of thecolor wheel 34 and to be outputted to the light processing element 41 ofthe image-forming system 4 for processing, thereby forming the infraredlight image.

It shall be noted that if the first light source device 31 of the secondembodiment adopts a white light emitting diode, then the illuminationsystem 3 of this embodiment may not comprise the switch device 35, inwhich case it is only necessary to, when the color wheel 34 iscontrolled according to the time sequence, to allow the infrared lightIR to pass through the transparent sector of the color wheel 34, andturn off the white light emitting diode of the first light source device31 so that it does not emit the visible light L. Furthermore, similar tothe first embodiment, variants of the first light source device 31 andthe second light source device 32 can be readily inferred by those ofordinary skill in the art. Similar to the first embodiment, in thesecond embodiment, the first light guiding device 33 may also have adichroic layer with opposite characteristics and the position of thefirst light source device 31 may be exchanged with that of the secondlight source device 32. In this way, the visible light L generated bythe first light source device 31 and the infrared light IR generated bythe second light source device 32 can still be outputted to theimage-forming system 4 to generate and project the visible light imageand the infrared light image.

The third embodiment of the present invention is shown in FIG. 5.Different from the aforesaid embodiments, in the third embodiment of thepresent invention, the image-forming system comprises four lightprocessing elements 42 a, 42 b, 42 c, 42 d and a second light guidingdevice 36. The visible light generated by the first light source deviceis divided into the red light R, the green light G and the blue light B.In this embodiment, the first light source device may comprise a redlight source 311 generating the red light R, a green light source 312generating the green light G and a blue light source 313 generating theblue light B to generate the red light R, the green light G and the bluelight B respectively. The red light R, the green light G, and the bluelight B generated by the first light source device and the infraredlight IR generated by the second light source device 32 arecorrespondingly outputted to the four light processing elements 42 a, 42b, 42 c, 42 d respectively to make the red light R form the red lightimage, make the green light G form the green light image, make the bluelight B form the blue light image and make the infrared light IR formthe infrared light image respectively.

In reference to FIG. 5, the second light guiding device 36 of theillumination system 3 selectively guides the red light image, the greenlight image and the blue light image so that the red light image, thegreen light image and the blue light image are combined into a visiblelight image for output to the first light guiding device 33.

The first light guiding device 33 guides the visible light image and theinfrared light image to the image-forming system and projects themoutward. In this embodiment, due to the characteristics of the dichroiclayer of the first light guiding device 33, the visible light image willpass through the first light guiding device 33 to enter theimage-forming system, and the infrared light image will be reflected bythe first light guiding device 33 into the image-forming system.

Preferably, in this embodiment, the red light source 311, the greenlight source 312 and the blue light source 313 come from a red lightemitting diode that generates the red light R, a green light emittingdiode that generates the green light G and a blue light emitting diodethat generates the blue light B respectively. Alternatively, the redlight source 311, the green light source 312 and the blue light source313 of the first light source device are a red laser light source, agreen laser light source and a blue laser light source respectively.Further, as described above, the light emitting diodes and the laserlight sources may be used in combination; and the green light source 312may also be obtained through the excitation of a green phosphor by theblue laser light source or the blue light emitting diode. Furthermore,the second light guiding device 36 is preferably selected from a groupconsisting of an X-cube and an X-plate to selectively guide and combinethe red light image, the green light image and the blue light image toform the visible light image.

It can also be readily inferred by those of ordinary skill in the artthat the first light guiding device 33 of the third embodiment may havea dichroic layer with opposite characteristics and that the positions ofthe first light source device (the red light source 311, the green lightsource 312 and the blue light source 313 as shown in FIG. 5) togetherwith the corresponding light processing elements 42 a, 42 b, 42 c aswell as the second light guiding device 36 may be exchanged with thepositions of the second light source device 32 together with thecorresponding light processing element 42 d. In this way, the firstlight guiding device 33 can also reflect the visible light L generatedby the first light source device to the image-forming system, and allowthe infrared light IR generated by the second light source device 32 topass therethrough to the image-forming system, thereby generating andprojecting the visible light image and the infrared light image.

In the third embodiment, the first light source device may also notcomprise the red light source 311, the green light source 312 and theblue light source 313 that generate the red light R, the green light Gand the blue light B respectively, but only comprise a light sourcegenerating a white light. In this case, by means of correspondingfilters, the white light generated by the first light source device isfiltered into the red light R, the green light G and the blue light Brespectively, which are then guided by optical elements to thecorresponding light processing elements 42 a, 42 b, 42 c respectively.

According to the above descriptions, the present invention provides anillumination system for a projection device, which can generate avisible light image and an infrared light image. In the presentinvention, the infrared light image is generated by processing asubstantially pure infrared light that is directly generated by a lightsource. Unlike other conventional night vision simulation systems, theillumination system of the present invention can generate both aninfrared light image and a visible light image in the same apparatuswithout the need of complicated parts and apparatuses and without theneed of an infrared light filter for filtering and generating theinfrared light. Thereby, problems such as a significant decrease in theluminance of the infrared light image and generation of massive heatenergy in the infrared light filter due to absorption of massive lightenergy that is filtered out are avoided.

The above disclosure is related to the detailed technical contents andinventive features thereof. People skilled in this field may proceedwith a variety of modifications and replacements based on thedisclosures and suggestions of the invention as described withoutdeparting from the characteristics thereof. Nevertheless, although suchmodifications and replacements are not fully disclosed in the abovedescriptions, they have substantially been covered in the followingclaims as appended.

What is claimed is:
 1. An illumination system for a projection device,the projection device having an image-forming system, the illuminationsystem comprising: a first light source device generating a visiblelight; a second light source device directly generating a substantiallypure infrared light; a first light guiding device guiding the visiblelight and the infrared light; and a switch device disposed between thefirst light source device and the first light guiding device to controlthe visible light entering the first light guiding device; wherein theillumination system outputs the visible light and the infrared light tothe image-forming system for processing to make the visible light form avisible light image and make the infrared light form an infrared lightimage.
 2. The illumination system as claimed in claim 1, wherein thesecond light source device comprises an infrared light emitting diode oran infrared laser light source.
 3. The illumination system as claimed inclaim 1, wherein the image-forming system of the projection devicefurther comprises a light processing element, and the first lightguiding device guides and outputs the visible light and the infraredlight to the light processing element to make the visible light form thevisible light image and make the infrared light form the infrared lightimage.
 4. The illumination system as claimed in claim 3, wherein thefirst light source device is a white light source, the illuminationsystem further comprises a color wheel disposed between the first lightguiding device and the image-forming system, and the color wheelcomprising a red sector, a green sector, a blue sector, and atransparent sector filters the visible light into a red light, a greenlight, and a blue light respectively by time sequence control and allowsthe infrared light to pass through the transparent sector.
 5. Theillumination system as claimed in claim 4, wherein the first lightsource device is a high intensity discharge (HID) lamp or an ultra highpressure (UHP) lamp.
 6. The illumination system as claimed in claim 4,wherein the first light source device comprises a white light emittingdiode.
 7. The illumination system as claimed in claim 3, wherein thefirst light source device comprises a red light emitting diode, a greenlight emitting diode and a blue light emitting diode emitting a redlight, a green light, and a blue light respectively by time sequencecontrol.
 8. The illumination system as claimed in claim 3, wherein thefirst light source device comprises a red laser light source, a greenlaser light source, and a blue laser light source emitting a red light,a green light, and a blue light respectively by time sequence control.9. The illumination system as claimed in claim 3, wherein the lightprocessing element is a liquid crystal display (LCD) element, a digitalmicromirror device (DMD), or a liquid crystal on silicon (LCOS) element.10. The illumination system as claimed in claim 1, wherein the firstlight guiding device comprises a dichroic layer allowing the visiblelight to pass therethrough and reflecting the infrared light to theimage-forming system.
 11. A projection device comprising: anillumination system comprising: a first light source device generating avisible light; a second light source device directly generating asubstantially pure infrared light; a first light guiding device guidingthe visible light and the infrared light; and a switch device disposedbetween the first light source device and the first light guiding deviceto control the visible light entering the first light guiding device;and an image-forming system receiving the visible light and the infraredlight, wherein the image-forming system receives the visible light andthe infrared light guided from the first light guiding device so as tomake the visible light form a visible light image and make the infraredlight form an infrared light image.
 12. The projection device as claimedin claim 11, wherein the second light source device comprises aninfrared light emitting diode or an infrared laser light source.
 13. Theprojection device as claimed in claim 11, wherein the image-formingsystem of the projection device further comprises a light processingelement, and the first light guiding device guides and outputs thevisible light and the infrared light to the light processing element tomake the visible light form the visible light image and make theinfrared light form the infrared light image.
 14. The projection deviceas claimed in claim 13, wherein the first light source device is a whitelight source, the illumination system further comprises a color wheeldisposed between the first light guiding device and the image-formingsystem, and the color wheel comprising a red sector, a green sector, ablue sector, and a transparent sector filters the visible light into ared light, a green light, and a blue light respectively by time sequencecontrol and allows the infrared light to pass through the transparentsector.
 15. The projection device as claimed in claim 13, wherein thefirst light source device comprises a red light emitting diode, a greenlight emitting diode, and a blue light emitting diode emitting a redlight, a green light, and a blue light respectively by time sequencecontrol.
 16. The projection device as claimed in claim 13, wherein thefirst light source device comprises a red laser light source, a greenlaser light source, and a blue laser light source emitting a red light,a green light, and a blue light respectively by time sequence control.